The present invention relates to a system and method for processing command signals, such as command signals for an electro-hydraulic control valve which operates a hydraulic device.
It is known to provide work vehicles, such as agricultural tractors, with a loader having a bucket which is movable by a hydraulic bucket cylinder. It is known to control the bucket cylinder with a conventional electro-hydraulic (EH) selective control valve (SCV), which, in turn, is controlled by an electronic valve controller. Bucket position and movement commands are generated by a control lever which is manipulated by an operator. In some commercially available systems, the position of the lever is monitored by an electronic lever unit which is communicated with the electronic valve controller. For example, in John Deere 7030 tractors, the lever and the electronic lever unit are mounted on an armrest in the tractor cab, and the electronic lever unit is communicated with a remote valve controller via a relatively slow speed serial communications data link.
In such systems, the response of the EH valve response is dependent upon the sample rate of the control lever position, the serial transmission rate of the serial data link and update rate at which the valve controller updates the valve command signal which is communicated to the SCV.
Typically, with such a system the actual bucket position and movement will not accurately match the control lever position and movement because of the slow serial communications data link. In addition, delays in the system may result in SCV conditions which conflict with the control lever. In some situations, such as when it is desired to dislodge debris from a loader bucket, an operator may desire to produce a vigorous and rapid SCV response by rapidly moving the control lever. If the transmission rate of the lever position to the EH valve controller is too slow, the SCV will typically not respond as desired by the operator, and the bucket movement may not be abrupt enough to loosen the debris. During a worst case, the transmission of the lever position over the serial communications link may occur when the control lever is near its center position instead of at maximum displaced position. As a result the lever command signal may not match the actual lever position and desired movement of the bucket may not be achieved.